Jointly as trustees



Sept. 13, 193. s. T/C ARTER ADJUSTABLE PITCH PROPELLER Filed April 9, 1930 4 Sheets-Sheet l QN R Q mm MM QN nazu-ron Sept. 13, 1932. s. T. CARTER ADJUSTABLE PITCH PROPELLER 4 Shets-Sheet 2 Filed April 9, 1930 P 13, 1932- s. 'r. CARTER ADJUSTABLE PITCH PROPELLER Filed April 9, 1930 4 Sheets-Sheet 5 &\ 3 W 3 m S N 7% Q NQ SQ Q m J N m6 w%\ mam u a 3 .3 am 8N Sept; 13, 1932. s. T. CARTER I ADJUSTABLE PITCH PROPELLER Filed April 9. 1930 4 sheets-Sheet 4 w mw ' INVENTOR A I call/Z 014 MMU WWW

- mechanism shown In Fig. 7 taken on line Patented Sept. 13, 1932 UNITED STATES PATENT OFFICE SIDNEY T. CARTER, OF PARNASSUS, PENNSYLVANIA, ASSIGNOR TO HIMSELF AND ROBERT E. LAN KFOED, QF PITTSBURGH, PENNSYLVANIA, JOINTLY TRUSTEES ADJUSTABLE PITCH PROBELLER Thisinvention relates to propellers for use in aeroplanes and in articular to mechanism for changing the pitc ofthe propellers while rotating or in motion. J

An object of this invention is the provision of a pitch changing means for propellers that shall be simple in construction, comparatively inexpensive to manufacture and more efficient and positive in action than those heretofore proposed; a

Other objects of the invention will, in part,

, be apparent and will, in part, be obvious-from the following description taken in conjunction with the accompanying drawings.

The invention comprises the novel details of construction and'combination of parts inore'fully hereinafter described and par ticularly pointed out in the claims.

In the accompanying drawings which form part of the specification 'and in which like reference characters designate like parts in all the views Figure 1 is a part1 al .view in section of a propeller 'hub'and propeller blades rotatably mounted thereon about their longitudinal axes, the section being taken along said longitudinal axes of the prQpellers;

Fig. 2 is a partial view in side elevation of the propeller mechanism arranged and constructed in accordance with the invention;

Fig. 3 is a fragmentary view in side elevation of the clamps shown in Figs. 1 and 2;

Fig. 4 is a view in section taken on line IV IV of Fig. 2; 7

Fig. 5 is a partial view in front elevaiiion of the propeller mechanism shown in ig. 2; Fig. 6 is a view in longitudinalsection of a detail embodied in'the mechanism for re-' Fig. 7 is a partial view in rear or back elevation of the propeller mechanism shown in v a Fig. 5 and Fig. 8 is a partial view in section of the III-V n thereof.

rotatably "mounted about their longitudinal 1930. Serial No. 442.801.

place on the hub 10 by clamps 12.

The hub 10 is preferably made of a high grade steel possessing the necessary qualities of strength required of hubs employed inaeroplane service. The hub in the process of manufacture is made from a solid forging of steel or an alloy and machined to provide a splined' bore 13 for receiving the power or propeller shaft. The hub is-bored also at 14, the axis of which is at right angles to the splined bore 13. The portions of the hub 10, about the bore 14 is machined in order to provide cylindrical extensions 15. for supporting the propellers 11. L

When the propellers 11 are in operative position on the hub, the cylindrical extensions 15 extend into the bases of the propellers as shown inlFig. 1.

Adjacent to the bases of the cylindrical extensions 15' are annular flanges 16. These flanges are in abutting relation with annular flanges 17 formed on the propeller blades 11 when mounted in place on the extensions 15. The clamping members 19 and 20 are knurled OrrQughened at 17 so that the clamps 12 and the flanges may be held together frictionally when the clamps are turned or .bscillated.v to change the pitch of the propellers.

The clamps 12 are of the split ring type and comprise two similar semi-circular members 19 and 20 (see Figs. 1 and 2) of substantially U-sh e or channel shape in section.

Stated more specifically the semi-circular member 19 forming part of the clamp 12 includes annular depending flanges'21 and 22. a'ndthe member 20 includes annular depending flanges 23 and 24. The members 19 and 20 of the clamps 12' are held firmly in clampingrelation or position-by means of bolts 25 that extend through bosses or'projections 26 and 27 formed integral with the members 19 and 20 of the clamps. The bolts may be tightened and drawn up into clamping position by lock nuts 28. I i p Since each propeller blade 11 is attached to the hub by independent clamps 12, one blade may be removed from the hub without removing the other. Also each blade may be individually adjusted without afl'ecting or adjusting the other blade.

In order that the propeller blades 11 may be turned easily about their longitudinal axes, anti-friction bearings are mounted on the hub 10 between the flanges 16 of the hub and the flanges 22 and 24 of the clamps 12 (see Fig. 1). The anti-friction bearings comprise a split ring 30 and a split ring 31 between which an annular ring 32 isplaced. The ring 32 carries anti-friction rollers 33. The split rings 30 and 31 are preferably made of hardened steel so that only a relatively small amount of wear will ta e place in operation or service. The split rings 30 fit snugly against the flanges 16 of the hub and the split rings 31 fit snugly against the flanges 22 and 24 of theclamps 12. By providing a clamp ring such as shown in 1 of the drawings and an anti-friction bearing of the type disclosed any type of propeller 11 may be employed; that is, the propeller may be of aluminum or steel or any form of alloy and need not be specially designed to accommodate the anti-friction bearing because the bearing is between one flange of the clamp and the flange on the hub and, therefore, does not come in contact with the propeller.

In the operation of aeroplanes, it is highly desirable to adjust the pitch of the propellers to a relatively low angle while the plane is climbing out of the field or taking-off. If the blades are set at a relatively low angle, it is possible for the plane to take-off in a much shorter distance than the propellers are set at a high pitch angle. If the blades are set at a relatively low angle or at an angle which will give a high rate of climbing, the plane cannot develop a high flying speed after it is in the air. It is also highly desirable in the operation of aeroplanes to be able to adjust the propellers to alhigh or flying anglewhen the plane is-in the air because a much higher speed may be obtained.

The ordinary propeller blades which are not adjustable as to the pitch angle are usually adjusted at an angle that will give fair- 1y good climbing speed and fairly good flying speed. This pitch angle is obviously a compromise; that is, both the climbing speed and the flying speed of the plane is sacrificed in order to obtain climbing and flying speeds J that are fairly satisfactory.

In order that the propeller 11 shown in the drawings may be adjusted to a relatively low angle, when climbing or taking-0E, so that the plane may take off in a relatively short distance, and to a relatively high angle after the plane is in the air to obtain a high flying speed, each blade 11 is provided with a lever 35 that is pivotally mounted on the hub 10 L at 36.

Asshown in Fig. 5 of the drawings levers 35 are mounted on opposite sides of the hub and are so placed that they are statically in balance with reference to the longitudinal axes of the hub bore 13. I

The manner of attaching the, levers 35 to the hub 10 is shown more p rticularly in Fig. 6 of the drawings. As th re shown a hole or recess 37 is bored in the body of the hub and provided with internal screw-threads 38. The lever 35 has astub shaft 39 formed integral therewith that extends into the bore or hole 37. The free end of the stub shaft 39 is provided with a washer 41. Washer 41 is prevented from moving off the end of the stub shaft 39 by means of a pin 42.

The stub shaft 39 is held inthe position shown in Fig. 6 of the drawings by means of a bushing 43. Bushing 43 is disposed about the stub shaft 39 and between thewasher 41 and the lever 35. By turning the bushing 43 into the hole or recess 37, the lever 35 isturnablymounted on the hub. This manner of attaching the lever. 35 to thehub is indicated also in broken" lines in Fig. 5 of the drawings. As shown in Fig. 6 the bushing 43 is provided at its upper end with a hexagonal nut 45 formed integrally with the bushing. By turningthe. nut 45 with a wrench or other suitable tool, the bushing may be positioned as shown in the drawings Each lever 35 is provided with a longitudinal slot 46 in which a pin 47 is disposed for movement back and forth along the slot- The pin 47 carries a nut or head 48 to steady the lever 35 as it oscillates about the stub shaft 39 and also to prevent the pin from screw-thread engagement withthe hub 10.

Worm 50 is provided with a plurality of tapped or screw-threaded holes 53, 54 and 55, each located at different radial distances from the center of rotation of the gear. The screw-threaded or tapped openings 53 to 55, inclusive, aretapped so as to receive or ac- ,commodate the pin 47. By placing the pin 47 in the desired tapped hole the are through which the'lever 35 oscillates may be varied according to the variations in pitch angle required to suit flying conditions and also according to the power characteristics and size of the particular motor employed.

The levers 35 are mechanically connected to the clamps 12 of the propellers by connecting links 59 such as illustrated in Fig. 4 of the drawings. The connecting links 59 have ball-and-socket connections with the lever 35- has a spherical head 67 that is nested in the spherical complemental recesses 62 and 63 of the plates 60 and 61.

The link 59 is connected to the clamp 12 by a pin 68 that has screw-thread engagement with a boss or lug 69 formed integral with the member 19 of the clamp as shown more particularly in Fig. 2 of the drawings. The

upper end of the pin 68 is provided with a spherical head 70 that is nested in the spherical complemental recesses 64 and 65 of the link 59.

By means of the ball-and-socket connection of the links 59 to the levers 35 and the clamps 12, the propellers 11 may becaused to reciprocate through a predeterminedmngle as the links 35 are oscillated by the gear 50. The propellers when in one extreme position are in climbing or low angle position, and when in the other positon are in flying or high angle position.

Gear 50 meshes with a worm 72 carried on a jack shaft 73. The jack shaft 73 is journalled in spaced lateral extending arms 74 and 75 of a U-shaped yoke 76. The yoke 76 formed integral with the hub' 10 as shown more particularly in Fig. 7 of the drawings. Jack shaft 73 carries a thrust bearing 77 between the worm 72 and the arm 75 of the yoke.

On one end of the jack shaft 73, a pinion 78 is fixedly mounted. Pinion 78 has spiral teeth thereon that mesh with a worm 80 anounted concentrically about the longitudinal axis of the splined bore 13 of the hub. The worm 80 is free to turn on a locking sleeve 81 (see Figs. 1, 2 and 8) which holds theworm in position on the hub 10. The locking sleeve 81- is disposed between the hub and the worm 80 and has screw-thread engagement with the hub at 83 as shown more particularly in'Figs. 1 and 8. Locking sleeve 81 is provided with an annular shoulder 82 that bears against the worm 80 to hold it in place. An annular shoulder 84 on the sleeve bears/ against the end of the hub so that when the slee is turned into locking position, sufiicieu. friction is developed between the. hub

and the shoulder 84 and the screw-threads 83 to hold the clamping sleeve in its operative position.

Worm 80 carries an annular brake drum 86 that is formed, preferably, as an integral part thereof. The brake drum 86 coacts with a brake band 87 that is secured to an annular brake shoe 88. Brake shoe 88 is pivotally mounted on a fork-like member 89-which in turn is pivoted on a stub shaft 90. The lower end of the fork-like member 89 is pivoted at 91 toa brake rod 92. The opposite end of the brake rod 92 is pivotally connected at 9.3 to a brake lever 94 that is pivoted on a lixed shaft or pivot 95.

In practice the brake lever 94 is mounted in the cockpit of the plane'and is manually operable by the pilot. When it isdesired to change the pitch of the propellers, the pilot pulls the brake lever 94 in the direction of the arrow 96 whereupon the rake shoe 88 is actuated to a position in w ich the brake lining 87 frictionally engages the brake drum 86. The friction betweenthe brake lining 87 and the brake dru m 86 causes the form 80 to move relatively to the hub 10 as it rotates about the longitudinal axis of the splined bore 13. This relative movement between the worm and the hub'10 is such that the hubrotates faster than the worm. For this reason the pinions 78 on the jack shafts 7 3 will be caused to roll by the worm 80. As the spiral pinions 78 roll,'the jack shafts 73 will turn to thereby turn the worms72 which, as stated herebefore, are in mesh with the worms 50.

As the worms 50 turn, the levers 35 are caused to oscillate bymovement of the pins 47 in the longitudinal slots 46 of the levers 35. This oscillation ,of the levers 35 is transmitted to the clamps 12, and as the fianges17 of the propellers frictionally engage the knurled surfaces 17 of the clamps '12, the propellers 11 will be turned in opposite di- I rections about the longitudinal axes.

Inorder that the pilot or operator may know what the angular position of the blades is at any particular time, an indicator or pointer 100 is provided that cooperates with. a graduated scale 101. The scale 101 may be calibrated in terms of pitch angle so that when the pointer or indicator 100 is adjusted to any particular division on the scale 101, the operator may know'what the pitch angle of the propellers 11 is at any particular time.

The indicator or pointer 100 is operated by an annular ring 102 that moves longitu dinally along the axis of the splined bore 13 of the hub as the clamps 12 turn about the longitudinal axes of the propellers 11. Movement of the annular ring 102 is transmitted to thepointer or indicator 100 through a link 103 Which in turn is pivotally connected to a link 104. Link 104 is pivotally connected at 105 to the pointer or indicator 100.

The link 103 is biased towards engagement with the annular ring 102 by means ofa 115 spring 107 disposed about the link 103 and mounted in a sleeve or cylinder 108. The spring 107.0perates between a closure 109 of the cylinder or sleeve 108 and a disc 110 secured to the link 103. 7

It may be assumed that the position of the pointer 100 as shown in Fig. 2 indicates the high pitch angle or flying angle of the propeller. blades 11 and that the opposite end of the scale 101 represents the position the pointer 100 will take when the propellers 11 have been adjusted to a relatively low pitch angle or climbing angle. The climbing pitch and the high or flying pitch angle of the propellers may be designated by the reference character F.

In the operation of the mechanism whereby the pitch angle of the propellers 11 may be varied between climbing and flying pitch angles, respectively, the pilot or operator observes the position of the pointer 100 while the brake leverl 94 is held in the position in whichythe brake is caused to engage the brake drum 386 of worm 80. When the pointer 100 .s adjacent to the point F on the scale, the brake handle 94 is released whereby rotation of the propellers 11 about their longitudinal axesis stopped when in the high pitch angle or flying position.

, To return or adjust the propellers 11 to the 3 low /pitch angle forclimbing, the operator or pilot operates the'brake lever 94 and holds it in braking position until the pointer 100 is adjacent to the point C on the scale 101.

' When the pointer reaches this position, the

operator or pilot releases the brake handle 94 whereby the blades are stopped in their climbing or low pitch angle position. Obvi- I ously, the pilot may adjust the pitch angle to any intermediate value.

The annular ring 102 is mounted on legs I 111, that move back and forth through slots or apertures 112 formed instub shafts 113 (see Fig. 8). The stub shafts 113 have screw-thread engagement with lugs or bosses 11.4 formed integral with the hub 10. Stub shafts 113 carry rollers 115 that engage the underside of the brake drum 86. These rollers 115 prevent the worm 80, from sliding inwardly and longitudinally along the hub 10.

The inner ends of the legs 111 are bent at an angle so as to provide lateral extensions or feet 116. The extensions or feet 116 are yieldingly held into engagement with the links 59 by coil springs 117 located between the extensions or feet 116 and the stub shafts 113.

When the propeller blades 11 are rotated about their longitudinal axes by the levers 35, the links 59 will cause the legs 111 attached to the annular ring 102 to move in the slots or apertures 112 of the stub shafts 113. The direction in which the annular ring 102 moves is determined by the direction in which the links 59 move. The movement ofthe annular ring 102 is transmitted to the link or rod 103 whereby the pointer 100 is caused to move to indicate the pitch angle of the propellers 11., i

In order to follow through the operation of fithe adjustable pitch mechanism shown in the drawings, it may be assumed that the 'posi- .-.tion of thelever's 35, as shown in Fig. 2, is the position in" which the propellers 11 are set or adjusted to the high or flying pitch angle. This is theangle to which the propellers 11 are adjustediiwhen flying at any given altiemme tude. When the pilot is about to make a landing, the blades are adjusted to the low or climbing pitch angle, so as to decrease the speed of the plane.

To adjust the propellers 11 to the low or climbing pitch angle the brake handle 94 is operated in the direction of the arrow 96 so that the brake lining 87 carried by the brake shoe is actuated into braking engagement with the brake drum 86. The friction between th brake lining and the brake drum will cause the worm 80 to stop or approximately stop so that the pinions 78 will cause the worms 72 carried by the jack shafts 73 to turn the worms in opposite directions. Only one of the worms 50 is shown in Fig. 2 of the drawings; but it is to be understood that the other worm 50 is on the opposite side of the hub. The worm 50 shown in Fig. 2 will turn in a counter-clockwise direction and cause the lever 35 to turn on its pivot 36 (that on the stub shaft 39 shown in Fig 6) in a clockwise direction, thereby turning one of the propellers 11 in the direction indicated by the arrow 97. The worm 50 on the opposite side of the hub will turn its lever 35 in a clockwise direction, whereby the other propeller will be turned in the direction indicated by the arrow 98.

As the propellers 11 are turning in opposite directions about their longitudinal axes, the operator or pilot observes the position of the pointer 100 and when it reaches a point adjacent to division C on the scale 101, the brake is released to thereby stop the propellers 11 in the low or climbing pitch angle.

, If conditions are such that the pilot cannot make a landing with the plane, he may then direct his plane upwardly'to a higher elevation so that he may again prepare for a landing. Since the blades are in the climbing pitch angle, the motor may be running at or near its maximumspeed so that it may develop its maximum power for climbing. This is an advantageous feature since it often happens that a pilot must make a very steep climb in order to avoid striking trees or other obstructions, and if the blades are in a high pitch angle this cannot be done.

If the pilot is able to make a landing, the propeller blades 11 are caused to remain in their low or climbing pitch angle so that the blades will be inclined at the proper angle for taking-off the field in case the pilot is to make another flight. It is to be understood at this point that the propellers 11 will always be set in the low or climbing pitch angle when the plane is to take-off the field.

If it is to be assumed that the plane has taken-off the field and has climbed to an altitude suitable for continuousflying, the pilot will operate the brake handle 94 so that the brake lining 87 will engage the brake shoe 86. The worms 50'will then be caused to turn in the same direction as in the case where the pitch of the blades is adjusted to the low or climbing angle until the levers have been oscillated to the position shown in Fig. 2 of the drawings. The propellers 11 will then be in the high or flying pitch angle. When the propellers are in the high or flying pitch angle, the motor may be slowed down to a speed far below its maxi- I mum speed. Even though the motor has been slowed down to a value considerably below its maximum speed, the plane will movethrough the air at a high speed because the blades are set at a high pitch angle. This'is a desirable feature of the inventlon in that it saves unnecessary expenditure of power and wear and tear on the motor and the plane as a w ole because the vibration of the motor will not be so great at the lower motor speeds.

Since the pitch of the propellers 11 may be varied between predetermined limits by means of a single brake mechanism, the operation of changing the itch of the blades is very simple and is easi y accomplished.

By the invention herein disclosed, the propeller blades 11 may be oscillated through a predetermined angle about their longitudinal axes by means of a single brake mechanism which is mechanically connected to the propeller blades in such away that when the brake is in braking position, the pitch angle of the propellers is varied andmay be adjusted to the desired value. This adjustment is accomplished by a simple oscillating mechanical mechanism and by means of which the pitch angle of the blades may be adjusted to either a high value or a low value according to the particular conditions to be met in flying.

While only one embodiment of the invention has been shown and described, it is to be understood that various modifications and changes may be made therein without departing from the spirit and the scope of the invention. It is desired, therefore, that only such limitations shall be placed on the invention as are imposed by the prior art and the appended claims.

What I claim as new and desire to secure said lever having a longitudinal slot, a gear turnably mounted on the hub, a pin on said gear extending into the slot of said lever, a jack shaft on said hub, a worm on said shaft meshing with said gear, a gear on said shaft, a worm on said hub mounted concentrically with the cranl shaft bore thereof, saidconcentrically mounted worm meshing with the jack shaft gear, a. brake I drum on said concentrically mounted having a crank shaft bore therein, of a propeller blade mounted on the hub and turnable thereon about its longitudinal axis, a lever pivotally mounted on the hub and having one end pivotally connected to the propeller, and means for oscillating the lever in response to rotation of thehub about its crank shaft bore as an axis, whereby the pitch angle of said propeller is varied.

3. The combination with a propeller hub having a crank shaft bore therein, of a propeller blade mounted on the hub and turnable thereon about its longitudinal axis, a lever pivotally mounted on the hub and having .one end pivotally connected to the propeller blade, means for. oscillating the free end of said lever in response to rotation of the hub about its crank shaft bore as an axis, whereby the pitch angle of said propeller is varied and means for indicating the pitch angle of the propeller.

4. In combination with a propeller hub having a crank shaft bore therein and a of said gear the lever is oscillated to oscillate the propeller through a predetermined pitch angle, and means for rotating said gear in response to rotation of the hub about the crank shaft bore as an axis.

5. The ombination' with a propeller hub having a crank shaft bore therein, of a propeller blade turnably mounted on the hub, an oscillatory lever pivotally connected to said hub and said propeller blade, a worm turnably mounted on said hub, said worm being concentric with said hub bore, a brake drum on said worm, means operable by said worm to oscillate said lever and turn said propeller through a predetermined pitch angle in response to relative movement between the hub and worm, and brake mech- ,anism operable upon said brake drum to effect said relative movement.

6. In combi ation, a propeller hub having a propeller rotatably mounted thereon, means 7 for oscillating said propeller through a predetermined pitch angle, and a single brake mechanism for operating said oscillatlng means while the propeller is in motion.

7. In combination, a propeller hub having an annular flange thereon, a propeller on said hub, said propeller having a flange abutting said hub flange, a two-part clamping ring having depending flanges straddling the hub and propeller flanges, an oscillatable lever mounted on the hub, said lever having a pivotal connection with said twoart clamping ring, and a crank on said hu to oscillate the lever, thereby to vary the pitch angle of said propeller.

8. In combination, a propeller hub having an annular flange thereon, a propeller on said hub, said propeller having a flange abutting said hub flange, a two-part clamping ring having depending flanges straddlin the hub and propeller flanges, an oscillata le lever mounted on the hub, said lever having a pivotal' connection with said two-part clamping ring, a crank pivotally mounted on said hub arranged to oscillate said lever, and means for, at will, providing a driving connection between said'hub, while rotating, and said crank, thereby to turn said crank and efl'ect an oscillating movement of said lever.

9. In combination, a propeller hub having an annular flange thereon, a propeller on said hub, said propeller having a flange abutting said-hub flange, a two-part clamping ring having depending flanges straddling the hub and propeller flanges, an oscillatable lever mounted on the hub, a link having a ball-and-socket connection with said lever and said two-part clamping ring, and a crank turnably mounted on said hub to oscil late said lever, thereby to vary the pitch angle of said propeller.

10. In combination with a propeller hub having a crank shaft bore therein and a propeller blade on the hub, said bladebeing turnable about its longitudinal axis, of a lever pivotally connected to the hub and the propeller, a crank turnably mounted on the hub arranged to oscillate said lever, thereby to oscillate said propeller'through a predetermined pitch angle, and means for turning said crank in response to rotation of the hub. 11. In combination, a propeller hub having an annular flange thereon, a propeller on said hub, said propeller having a flange abutting said hub flange, a two-part clamping ring having depending flanges straddling the hub and propeller flanges, an oscillatable lever mounted on the hub, a link having a ball-and-soeket connection with said lever and said two-part clampin ring, a crank turnably mounted on said ub to oscillate said lever, thereby to vary the pitch angle of said propeller, and means, for, at times, establishing a driving connection between the hub and said crank when the hub is rotating about its crank shaft bore as an axis.

12. The combination with a ropeller hub, of a propeller blade mounted on said hub and turnable thereon about its longitudinal,

an oscillatory member pivotally axis mouhted on said hub and pivotally connected to said blade, a Worm turnablymounted on said hub and normally rotating therewith and means operable by said worm having a.

pin and slot connection with said member for oscillating said member.

' In testimony whereof, I have hereunto subscribed by name this 5th day of April, 1930.

smart 'll. C'llER. 

